In the past, as the type of rotary compressor having a plurality of cylinder chambers in the same plane, compressors configured such that their pistons and cylinders are rotated eccentrically relative to each other for the compression of refrigerant have been known in the art.
There is disclosed, for example, in JP-A-H06-288358 (herein after referred to as the patent document), a compressor (see FIG. 8 and FIG. 9 which is a cross-sectional view taken along line X-X in FIG. 8). This compressor (100) includes a hermetically sealed casing (110) which contains therein a compression mechanism (120) and an electric motor (not shown) severing as a drive mechanism for driving the compression mechanism (120).
The compression mechanism (120) has a cylinder (121) having a cylinder chamber (C1, C2) in the shape of a ring, and a ring-shaped piston (122) arranged in the cylinder chamber (C1, C2). The cylinder (121) has an outer cylinder part (124) and an inner cylinder part (125), which parts are arranged concentrically relative to each other, and the cylinder chamber (C1, C2) is defined between the outer cylinder part (124) and the inner cylinder part (125).
The ring-shaped piston (122) is connected through a piston base (160) in the shape of a circle to an eccentric part (133a) of a drive shaft (133) connected to the electric motor (not shown). In addition, the drive shaft (133) is rotatably supported by a main bearing (145a) of a bearing member (145) interposed between the compression mechanism (120) and the electric motor. On the other hand, the cylinder (121) is firmly secured by a fastening screw (152) to an overlying casing cover (151).
In addition, the ring-shaped piston (122) is configured such that it is rotated eccentrically relative to the center of the cylinder (121), with the outer peripheral surface being substantially in line contact through a microgap with the inner peripheral surface of the outer cylinder part (124), and with the inner peripheral surface being substantially in line contact through a microgap with the outer peripheral surface of the inner cylinder part (125).
An outer blade (123A) is arranged outside the ring-shaped piston (122). An inner blade (123B) is arranged so as to lie on an extension of the outer blade (123A). The outer blade (123A) is inserted in a blade groove formed in the outer cylinder part (124). And, the outer blade (123A) is biased inwardly in the radial direction of the ring-shaped piston (122) and its tip end is in pressure contact with the outer peripheral surface of the ring-shaped piston (122). On the other hand, the inner blade (123B) is inserted in a blade groove formed in the inner cylinder part (125). And, the inner blade (123B) is biased outwardly in the radial direction of the ring-shaped piston (122) and its tip end is in pressure contact with the inner peripheral surface of the ring-shaped piston (122).
In the way as described above, the outer blade (123A) separates the outer cylinder chamber (C1) into a high pressure chamber and a low pressure chamber. Likewise, the inner blade (123B) separates the inner cylinder chamber (C2) into a high pressure chamber and a low pressure chamber. And, in the compressor (100), as the ring-shaped piston (122) is rotated eccentrically, fluid is drawn into the low pressure chamber (C1-Lp, C2-Lp) of the cylinder chamber (C1, C2) while fluid is compressed in the high pressure chamber (C1-Hp, C2-Hp) of the cylinder chamber (C1, C2).